The broad, long-term objectives of this proposal are to elucidate the vascular dysfunction induced by sequestration of Plasmodium falciparum infected erythrocytes to the vasculature and to test novel approaches to improve vascular patency that will facilitate the identification of intelligent interventions for novel severe malara adjuvant therapeutic strategies. Of the five Plasmodium species that infect humans, infection with P. falciparum is the most lethal, causing severe malaria syndromes, and resulting in over half a million annual deaths. With the increasing resistance of parasites to artemisinin there is an urgent need for new preventative and therapeutic interventions. The concepts of this application are centered on the recent discoveries that certain variants of P. falciparum erythrocyte membrane protein 1 (PfEMP1) expressed on infected erythrocytes are intimately linked to the precipitation of severe malaria syndromes. Furthermore, these particular PfEMP1 variants bind to the endothelial protein C receptor (EPCR) expressed on vascular endothelial cells. EPCR is known for its essential role in the protein C system and is critical for the abilityof activated protein C (APC) to induce cytoprotective-signaling pathways that result in remarkable vascular and tissue protective effects in almost every organ system of the body, including the brain, lung, kidney, and liver. Our preliminary data show that the binding of PfEMP1 to EPCR results in an acquired protein C system deficiency, for which the genetic deficiencies are associated with severe thrombotic complications, increased susceptibility to inflammation, and neurological disability. One major goal is to characterize potential novel adjuvant therapies to restore vascular patency by enabling, augmenting, and/or bypassing protein C system functions. Another goal is to develop novel tools to enable studies on molecular mechanisms in vitro and proof-of-concept studies in vivo of PfEMP1-mediated interactions with vascular cells without a requirement for live parasite culturing capabilities. We propose that this will make malaria research more accessible and will greatly accelerate knowledge gathering on the pathogenesis of severe malaria. The team of PI's, consisting of Dr. Mosnier (Protein C system and EPCR), Dr. Weiler (genetically modified mouse models and the innate immune system), and Dr. Lavstsen (PfEMP1 and malaria), brings together the required expertise to successfully complete this multi-disciplinary project. Specific hypotheses will be tested based on the following two specific aims: (1) To characterize the vascular dysfunction induced by PfEMP1 binding to EPCR and to develop novel approaches for adjuvant therapy in severe malaria. These in vitro studies will focus on the effects of PfEMP1 on the protein C system. Multiple approaches will be tested for their ability to restore the anticoagulant and cytoprotective activities of APC, or to bypass the need for EPCR. (2) To enable in vivo investigations on the pathogenesis associated with PfEMP1 binding to EPCR. We will address the urgent need for in vivo investigations of the consequences of EPCR inactivation by PfEMP1 for vascular functions.